Why green light is on at the back of PC even though PC is off?

A green light at the back of a PC, even when it’s turned off, often indicates that the power supply unit (PSU) is still receiving power. This can happen if the PSU is in a standby mode, allowing certain components, like the motherboard or peripherals, to remain powered for features like Wake-on-LAN. Additionally, some systems have settings that allow the motherboard to receive power for quick startup or charging USB devices even when the PC is off. If the light is unexpected, it may be worth checking the power settings in the BiOS or inspecting the power supply.